IMPACT OF THE 2010 MACONDO OIL SPILL ON THE MARSHES IN BARATARIA BAY, TERREBONNE BAY, AND BRETON SOUND, LOUISIANA, U.S.A., USING LANDSAT AND ASTER DATA
Marsh loss varies spatially and temporally in the Mississippi delta marshes. Marshes located less than 40 km from the coast were less stable than freshwater and most brackish marshes. Vegetation health and marsh area from 1984-1992 were relatively stable with minor inter-annual fluctuations and only a few areas of localized marsh loss. By 1994, shoreline erosion, tidal creek erosion, and erosion of soil banks adjacent to canals had increased primarily in coastal marshes. Hurricane Ivan in 2004 caused little sustained damage. By comparison, Hurricanes Katrina and Rita in 2005 and Gustav and Ike in 2008 caused local extensive erosion of vegetation and the marsh substrate. Hurricane damage was concentrated in Caernarvon diversion freshwater and intermediate marshes showed the greatest damage; however, Naomi and West Point a La Hache diversions marshes were also badly affected. Coastal marshes largely showed less long-term hurricane damage than inland marshes.
Landsat and ASTER data suggest that the health of coastal marsh vegetation was not seriously impacted by the Macondo oil spill, although this determination is complicated by a 2011 marsh die back event independent of the oil spill. Although die back of oiled marsh vegetation was detected on the ground, the scale of the damage was typically far less than the spatial resolution of Landsat (30 m x 30 m) and ASTER (15 m x 15 m). To date, the Macondo oil spill has had relatively little impact on marsh vegetation health and area compared to the 2005 and 2008 hurricanes. In addition, the damage produced by the oil spill was less than the cumulative erosion that occurred between 1984 and April 2010.